1. Field of the Invention
This invention relates to an antenna, and more particularly to an antenna operable to transmit and receive signals across a range of frequencies whilst maintaining a uniform beam shape.
2. Description of the Related Art
There exist a number of applications in which it is desirable for an antenna to be able to scan across a broad range of frequencies. In some cases, it is further desirable for such antennas to provide broad spatial coverage. In order to be able to scan across a spatially large area, and provide consistency throughout the relevant frequency band, it is necessary for the beamwidth to remain constant throughout the relevant frequency range. This can be difficult, because the electrical size of any antenna aperture changes with frequency, normally resulting in a change of beam shape with frequency: as the frequency increases, the beam becomes narrower. A number of apodising technologies exist that can overcome these problems—for example, the effective aperture of an antenna comprising a number of antenna elements can be controlled by adjusting the signal amplitude at each element with frequency. However, these technologies are complex and expensive.
There thus exists a need for an antenna that, is both inexpensive and simple to fabricate whilst still achieving the functionality described above.